1. Technical Field
The present invention relates to a method for correcting density irregularity, a printing apparatus, and an imaging module.
2. Related Art
In a printing apparatus that ejects ink on a medium (for example, a paper surface) so as to print an image, band-like or streaky density irregularity (so-called banding) occurs in a main-scanning direction of a printing head that ejects ink, in some cases. By comparison, there is known a system that corrects such banding (for example, see JP-A-2006-305956).
In the system disclosed in JP-A-2006-305956, a medium (paper, cloth, a film, an OHP sheet, or the like), on which a correcting pattern is printed by a printing apparatus, is set in a scanner. The scanner has a line sensor and line scanning is performed by the line sensor such that the correcting pattern is read to acquire image data. Then, the read and acquired image data is transmitted to a computer from the scanner, and the computer acquires a correction value that is used to correct density irregularity, based on the image data.
Incidentally, in the system disclosed in JP-A-2006-305956, the medium, on which printing is performed by a printer, is reset in the scanner such that the scanner reads the correcting pattern through line scanning. In the reading of the image through the line scanning, a problem arises in that there is a limit to a reading speed and it takes a time to acquire the correction value (banding correction). In addition, in JP-A-2006-305956, since the medium, on which the printing apparatus has performed printing, need to be reset in the scanner, even in this respect, it takes a long time to perform the banding correction. Further, there is a shift between a position of the correcting pattern when the medium is set in the scanner and a position of the correcting pattern printed by the printer, and thus there is a possibility that there is a positional error even in a correction value.